Evaluation of two-breed composites alongside Angus or Hereford controls for growth, reproduction, maternal, and carcass traits

Abstract

Angus (A) and Hereford (H) cows at one location and A cows at a second location were used to generate purebred controls and six first-cross (FI) types of calf. Foundation sires were A, H, Friesian (F), Jersey (J), and South Devon (Sd) at Location 1, generating FH, FA. JA, SdA, and HA (plus AH) FI calves, and at Location 2 sires were A and Blonde d' Aquitaine (Ba), generating BaA Fis. Sire breeds were selected as potentially contributing to productive crossbred cows, based on previous FI cow comparisons. In subsequent years F2, F3, and F4 calves were produced from each of the two-breed crosses, with overlapping generations and contemporary controls providing balanced comparisons of breed types and generations. The experiment consisted of 395 unique sires and 5243 calves born in 1973-88 at Location 1 and 105 different sires and 2404 calves born in 1976-86 at Location 2. Growth, reproductioQ, maternal, and carcass traits were studied. Heterosis was estimated from HA (plus AH) and purebred A and H animals, but only breed x A 93009 generation effects were estimated from the other two-breed crosses because of the absence of reciprocal FI matings. Heterosis from HA crosses was 3.5 and 6.3% for direct effects on weaning and yearling weights respectively, and 9.0% for the maternal (i.e. Fl cow) effect on weaning weight. For reproduction of FI HA cows, heterosis was 15.2% for calf crop weaned per cow joined, 25.4% for productivity (calf weaning weight per cow joined), and 18.1 % for an efficiency ratio (i.e. productivity/ average cow weight). Over all six two-breed crosses, relative to purebred controls, advantages of Fis averaged 4.4 and 8.1 % for direct effects on weaning and yearling weights respectively, and 13.3% for the . maternal (FI cow) effect on weaning weight. For reproduction, the FI cow advantage over controls averaged 9.7% for calf crop weaned per cow joined (range -7.3 to +15.2%), 24.7% for productivity (range -8.9 to 47.3%), and 16.8% for the efficiency ratio (range -15.7 to +36.3%). For the efficiency ratio, breed types were ranked FH (greatest), JA, FA, HA, SdA, A, H, and BaA. On average, the F3 and F4 calves out-perfonned the Fls by 6.3% in weaning weight but were similar to Fls in yearling weight, whereas for maternal weaning weight the means for F3 cows' calves were 3.4% below those for FI cows. For reproduction, averages of F3s were below those of Fls but superior to the purebreds by 7.2, 17.7, and 16.3% for calves weaned per cow joined, productivity, and the efficiency ratio respectively. There were also significant breed-group differences in carcass composition.

Effect of age of pre‐ and post‐pubertal castration of bulls on growth rates and carcass quality

“…Changing the age at castration is less likely to affect classification at higher levels of carcass fatness. The higher birthweight, liveweight, carcass weight, and growth rate from birth to 12 months of age of HF compared with A was consistent with earlier reports on the effects of cross breeding and hybrid vigour on these traits and the superior growth of calves reared on Friesian cows (Everitt et al 1978;Morris et al 1993). There were no differences between A and HF for any of the measures of carcass fatness.…”

Reproductive performance of Angus, Hereford, Salers and Nellore crossbred females: Additive and non‐additive effects

“…(1991) and Morris et al. (1993) obtained similar results A/H, with days to calving values of −6.2 and −2.5, respectively.…”

“…Morris et al. (1993) reported −6.2 days to calve for A cows compared to H cows in New Zealand. Williams et al.…”

Genetic parameters for growth, puberty, and beef cow reproductive traits in a puberty selection experiment

“…Heritability estimates for PR in the present study (Table 4) were 0.12 ± 0.05 (1-year-olds), 0.08 ± 0.06 (2-year-olds), and 0.037 ± 0.046 (cows mated at 3 years of age or older); for comparison, there are two other independent published New Zealand estimates for beef cattle, both of 0.035 ±0.015 (Morris et al 1993b, 500 paternal half-sib groups in a multigeneration study; Morris et al 1993c, 161 sire groups in a first-cross cow study). CD in Table 4 had a heritability of 0.091 ± 0.036, compared with values of 0.067 ± 0.028 (Morris et al 1993b) and 0.022 ± 0.019 (Morris et al 1993c). CCI had a value in Table 4 of 0.11 ± 0.04, and whilst there are no other estimates for this trait in New Zealand beef cattle for comparison, estimates from New Zealand dairy cattle were 0.02 ± 0.004 and 0.01 ± 0.003 in first and second lactation cows, respectively (Grosshans et al 1997).…”

“…(There were no significant selection line differences in twinning rate, where the overall mean was 3.1%, or in abortions, where the overall mean was 0.3%.) For all cow traits, data were also screened to remove cows in subfertile bull mating groups (defined consistently in Genetics Section cattle research at Ruakura as those with a PR of <60%; e.g., Morris et al 1993b). The Control line calvings (1985 to 1992), which were the result of artificial insemination, were also excluded for the PR trait.…”